xref: /dragonfly/sys/vfs/hammer/hammer_blockmap.c (revision 4a65f651)
1 /*
2  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
3  *
4  * This code is derived from software contributed to The DragonFly Project
5  * by Matthew Dillon <dillon@backplane.com>
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  *
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in
15  *    the documentation and/or other materials provided with the
16  *    distribution.
17  * 3. Neither the name of The DragonFly Project nor the names of its
18  *    contributors may be used to endorse or promote products derived
19  *    from this software without specific, prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  *
34  * $DragonFly: src/sys/vfs/hammer/hammer_blockmap.c,v 1.27 2008/07/31 22:30:33 dillon Exp $
35  */
36 
37 /*
38  * HAMMER blockmap
39  */
40 #include "hammer.h"
41 
42 static int hammer_res_rb_compare(hammer_reserve_t res1, hammer_reserve_t res2);
43 static void hammer_reserve_setdelay_offset(hammer_mount_t hmp,
44 				    hammer_off_t base_offset, int zone,
45 				    struct hammer_blockmap_layer2 *layer2);
46 static void hammer_reserve_setdelay(hammer_mount_t hmp, hammer_reserve_t resv);
47 
48 /*
49  * Reserved big-blocks red-black tree support
50  */
51 RB_GENERATE2(hammer_res_rb_tree, hammer_reserve, rb_node,
52 	     hammer_res_rb_compare, hammer_off_t, zone_offset);
53 
54 static int
55 hammer_res_rb_compare(hammer_reserve_t res1, hammer_reserve_t res2)
56 {
57 	if (res1->zone_offset < res2->zone_offset)
58 		return(-1);
59 	if (res1->zone_offset > res2->zone_offset)
60 		return(1);
61 	return(0);
62 }
63 
64 /*
65  * Allocate bytes from a zone
66  */
67 hammer_off_t
68 hammer_blockmap_alloc(hammer_transaction_t trans, int zone, int bytes,
69 		      hammer_off_t hint, int *errorp)
70 {
71 	hammer_mount_t hmp;
72 	hammer_volume_t root_volume;
73 	hammer_blockmap_t blockmap;
74 	hammer_blockmap_t freemap;
75 	hammer_reserve_t resv;
76 	struct hammer_blockmap_layer1 *layer1;
77 	struct hammer_blockmap_layer2 *layer2;
78 	hammer_buffer_t buffer1 = NULL;
79 	hammer_buffer_t buffer2 = NULL;
80 	hammer_buffer_t buffer3 = NULL;
81 	hammer_off_t tmp_offset;
82 	hammer_off_t next_offset;
83 	hammer_off_t result_offset;
84 	hammer_off_t layer1_offset;
85 	hammer_off_t layer2_offset;
86 	hammer_off_t base_off;
87 	int loops = 0;
88 	int offset;		/* offset within big-block */
89 	int use_hint;
90 
91 	hmp = trans->hmp;
92 
93 	/*
94 	 * Deal with alignment and buffer-boundary issues.
95 	 *
96 	 * Be careful, certain primary alignments are used below to allocate
97 	 * new blockmap blocks.
98 	 */
99 	bytes = (bytes + 15) & ~15;
100 	KKASSERT(bytes > 0 && bytes <= HAMMER_XBUFSIZE);
101 	KKASSERT(zone >= HAMMER_ZONE_BTREE_INDEX && zone < HAMMER_MAX_ZONES);
102 
103 	/*
104 	 * Setup
105 	 */
106 	root_volume = trans->rootvol;
107 	*errorp = 0;
108 	blockmap = &hmp->blockmap[zone];
109 	freemap = &hmp->blockmap[HAMMER_ZONE_FREEMAP_INDEX];
110 	KKASSERT(HAMMER_ZONE_DECODE(blockmap->next_offset) == zone);
111 
112 	/*
113 	 * Use the hint if we have one.
114 	 */
115 	if (hint && HAMMER_ZONE_DECODE(hint) == zone) {
116 		next_offset = (hint + 15) & ~(hammer_off_t)15;
117 		use_hint = 1;
118 	} else {
119 		next_offset = blockmap->next_offset;
120 		use_hint = 0;
121 	}
122 again:
123 
124 	/*
125 	 * use_hint is turned off if we leave the hinted big-block.
126 	 */
127 	if (use_hint && ((next_offset ^ hint) & ~HAMMER_HINTBLOCK_MASK64)) {
128 		next_offset = blockmap->next_offset;
129 		use_hint = 0;
130 	}
131 
132 	/*
133 	 * Check for wrap
134 	 */
135 	if (next_offset == HAMMER_ZONE_ENCODE(zone + 1, 0)) {
136 		if (++loops == 2) {
137 			result_offset = 0;
138 			*errorp = ENOSPC;
139 			goto failed;
140 		}
141 		next_offset = HAMMER_ZONE_ENCODE(zone, 0);
142 	}
143 
144 	/*
145 	 * The allocation request may not cross a buffer boundary.  Special
146 	 * large allocations must not cross a large-block boundary.
147 	 */
148 	tmp_offset = next_offset + bytes - 1;
149 	if (bytes <= HAMMER_BUFSIZE) {
150 		if ((next_offset ^ tmp_offset) & ~HAMMER_BUFMASK64) {
151 			next_offset = tmp_offset & ~HAMMER_BUFMASK64;
152 			goto again;
153 		}
154 	} else {
155 		if ((next_offset ^ tmp_offset) & ~HAMMER_LARGEBLOCK_MASK64) {
156 			next_offset = tmp_offset & ~HAMMER_LARGEBLOCK_MASK64;
157 			goto again;
158 		}
159 	}
160 	offset = (int)next_offset & HAMMER_LARGEBLOCK_MASK;
161 
162 	/*
163 	 * Dive layer 1.
164 	 */
165 	layer1_offset = freemap->phys_offset +
166 			HAMMER_BLOCKMAP_LAYER1_OFFSET(next_offset);
167 	layer1 = hammer_bread(hmp, layer1_offset, errorp, &buffer1);
168 	if (*errorp) {
169 		result_offset = 0;
170 		goto failed;
171 	}
172 
173 	/*
174 	 * Check CRC.
175 	 */
176 	if (layer1->layer1_crc != crc32(layer1, HAMMER_LAYER1_CRCSIZE)) {
177 		hammer_lock_ex(&hmp->blkmap_lock);
178 		if (layer1->layer1_crc != crc32(layer1, HAMMER_LAYER1_CRCSIZE))
179 			panic("CRC FAILED: LAYER1");
180 		hammer_unlock(&hmp->blkmap_lock);
181 	}
182 
183 	/*
184 	 * If we are at a big-block boundary and layer1 indicates no
185 	 * free big-blocks, then we cannot allocate a new bigblock in
186 	 * layer2, skip to the next layer1 entry.
187 	 */
188 	if (offset == 0 && layer1->blocks_free == 0) {
189 		next_offset = (next_offset + HAMMER_BLOCKMAP_LAYER2) &
190 			      ~HAMMER_BLOCKMAP_LAYER2_MASK;
191 		goto again;
192 	}
193 	KKASSERT(layer1->phys_offset != HAMMER_BLOCKMAP_UNAVAIL);
194 
195 	/*
196 	 * Dive layer 2, each entry represents a large-block.
197 	 */
198 	layer2_offset = layer1->phys_offset +
199 			HAMMER_BLOCKMAP_LAYER2_OFFSET(next_offset);
200 	layer2 = hammer_bread(hmp, layer2_offset, errorp, &buffer2);
201 	if (*errorp) {
202 		result_offset = 0;
203 		goto failed;
204 	}
205 
206 	/*
207 	 * Check CRC.  This can race another thread holding the lock
208 	 * and in the middle of modifying layer2.
209 	 */
210 	if (layer2->entry_crc != crc32(layer2, HAMMER_LAYER2_CRCSIZE)) {
211 		hammer_lock_ex(&hmp->blkmap_lock);
212 		if (layer2->entry_crc != crc32(layer2, HAMMER_LAYER2_CRCSIZE))
213 			panic("CRC FAILED: LAYER2");
214 		hammer_unlock(&hmp->blkmap_lock);
215 	}
216 
217 	/*
218 	 * Skip the layer if the zone is owned by someone other then us.
219 	 */
220 	if (layer2->zone && layer2->zone != zone) {
221 		next_offset += (HAMMER_LARGEBLOCK_SIZE - offset);
222 		goto again;
223 	}
224 	if (offset < layer2->append_off) {
225 		next_offset += layer2->append_off - offset;
226 		goto again;
227 	}
228 
229 	/*
230 	 * If operating in the current non-hint blockmap block, do not
231 	 * allow it to get over-full.  Also drop any active hinting so
232 	 * blockmap->next_offset is updated at the end.
233 	 *
234 	 * We do this for B-Tree and meta-data allocations to provide
235 	 * localization for updates.
236 	 */
237 	if ((zone == HAMMER_ZONE_BTREE_INDEX ||
238 	     zone == HAMMER_ZONE_META_INDEX) &&
239 	    offset >= HAMMER_LARGEBLOCK_OVERFILL &&
240 	    !((next_offset ^ blockmap->next_offset) & ~HAMMER_LARGEBLOCK_MASK64)
241 	) {
242 		if (offset >= HAMMER_LARGEBLOCK_OVERFILL) {
243 			next_offset += (HAMMER_LARGEBLOCK_SIZE - offset);
244 			use_hint = 0;
245 			goto again;
246 		}
247 	}
248 
249 	/*
250 	 * We need the lock from this point on.  We have to re-check zone
251 	 * ownership after acquiring the lock and also check for reservations.
252 	 */
253 	hammer_lock_ex(&hmp->blkmap_lock);
254 
255 	if (layer2->zone && layer2->zone != zone) {
256 		hammer_unlock(&hmp->blkmap_lock);
257 		next_offset += (HAMMER_LARGEBLOCK_SIZE - offset);
258 		goto again;
259 	}
260 	if (offset < layer2->append_off) {
261 		hammer_unlock(&hmp->blkmap_lock);
262 		next_offset += layer2->append_off - offset;
263 		goto again;
264 	}
265 
266 	/*
267 	 * The bigblock might be reserved by another zone.  If it is reserved
268 	 * by our zone we may have to move next_offset past the append_off.
269 	 */
270 	base_off = (next_offset &
271 		    (~HAMMER_LARGEBLOCK_MASK64 & ~HAMMER_OFF_ZONE_MASK)) |
272 		    HAMMER_ZONE_RAW_BUFFER;
273 	resv = RB_LOOKUP(hammer_res_rb_tree, &hmp->rb_resv_root, base_off);
274 	if (resv) {
275 		if (resv->zone != zone) {
276 			hammer_unlock(&hmp->blkmap_lock);
277 			next_offset = (next_offset + HAMMER_LARGEBLOCK_SIZE) &
278 				      ~HAMMER_LARGEBLOCK_MASK64;
279 			goto again;
280 		}
281 		if (offset < resv->append_off) {
282 			hammer_unlock(&hmp->blkmap_lock);
283 			next_offset += resv->append_off - offset;
284 			goto again;
285 		}
286 		++resv->refs;
287 	}
288 
289 	/*
290 	 * Ok, we can allocate out of this layer2 big-block.  Assume ownership
291 	 * of the layer for real.  At this point we've validated any
292 	 * reservation that might exist and can just ignore resv.
293 	 */
294 	if (layer2->zone == 0) {
295 		/*
296 		 * Assign the bigblock to our zone
297 		 */
298 		hammer_modify_buffer(trans, buffer1,
299 				     layer1, sizeof(*layer1));
300 		--layer1->blocks_free;
301 		layer1->layer1_crc = crc32(layer1,
302 					   HAMMER_LAYER1_CRCSIZE);
303 		hammer_modify_buffer_done(buffer1);
304 		hammer_modify_buffer(trans, buffer2,
305 				     layer2, sizeof(*layer2));
306 		layer2->zone = zone;
307 		KKASSERT(layer2->bytes_free == HAMMER_LARGEBLOCK_SIZE);
308 		KKASSERT(layer2->append_off == 0);
309 		hammer_modify_volume_field(trans, trans->rootvol,
310 					   vol0_stat_freebigblocks);
311 		--root_volume->ondisk->vol0_stat_freebigblocks;
312 		hmp->copy_stat_freebigblocks =
313 			root_volume->ondisk->vol0_stat_freebigblocks;
314 		hammer_modify_volume_done(trans->rootvol);
315 	} else {
316 		hammer_modify_buffer(trans, buffer2,
317 				     layer2, sizeof(*layer2));
318 	}
319 	KKASSERT(layer2->zone == zone);
320 
321 	layer2->bytes_free -= bytes;
322 	KKASSERT(layer2->append_off <= offset);
323 	layer2->append_off = offset + bytes;
324 	layer2->entry_crc = crc32(layer2, HAMMER_LAYER2_CRCSIZE);
325 	hammer_modify_buffer_done(buffer2);
326 	KKASSERT(layer2->bytes_free >= 0);
327 
328 	/*
329 	 * We hold the blockmap lock and should be the only ones
330 	 * capable of modifying resv->append_off.  Track the allocation
331 	 * as appropriate.
332 	 */
333 	KKASSERT(bytes != 0);
334 	if (resv) {
335 		KKASSERT(resv->append_off <= offset);
336 		resv->append_off = offset + bytes;
337 		resv->flags &= ~HAMMER_RESF_LAYER2FREE;
338 		hammer_blockmap_reserve_complete(hmp, resv);
339 	}
340 
341 	/*
342 	 * If we are allocating from the base of a new buffer we can avoid
343 	 * a disk read by calling hammer_bnew().
344 	 */
345 	if ((next_offset & HAMMER_BUFMASK) == 0) {
346 		hammer_bnew_ext(trans->hmp, next_offset, bytes,
347 				errorp, &buffer3);
348 	}
349 	result_offset = next_offset;
350 
351 	/*
352 	 * If we weren't supplied with a hint or could not use the hint
353 	 * then we wound up using blockmap->next_offset as the hint and
354 	 * need to save it.
355 	 */
356 	if (use_hint == 0) {
357 		hammer_modify_volume(NULL, root_volume, NULL, 0);
358 		blockmap->next_offset = next_offset + bytes;
359 		hammer_modify_volume_done(root_volume);
360 	}
361 	hammer_unlock(&hmp->blkmap_lock);
362 failed:
363 
364 	/*
365 	 * Cleanup
366 	 */
367 	if (buffer1)
368 		hammer_rel_buffer(buffer1, 0);
369 	if (buffer2)
370 		hammer_rel_buffer(buffer2, 0);
371 	if (buffer3)
372 		hammer_rel_buffer(buffer3, 0);
373 
374 	return(result_offset);
375 }
376 
377 /*
378  * Frontend function - Reserve bytes in a zone.
379  *
380  * This code reserves bytes out of a blockmap without committing to any
381  * meta-data modifications, allowing the front-end to directly issue disk
382  * write I/O for large blocks of data
383  *
384  * The backend later finalizes the reservation with hammer_blockmap_finalize()
385  * upon committing the related record.
386  */
387 hammer_reserve_t
388 hammer_blockmap_reserve(hammer_mount_t hmp, int zone, int bytes,
389 			hammer_off_t *zone_offp, int *errorp)
390 {
391 	hammer_volume_t root_volume;
392 	hammer_blockmap_t blockmap;
393 	hammer_blockmap_t freemap;
394 	struct hammer_blockmap_layer1 *layer1;
395 	struct hammer_blockmap_layer2 *layer2;
396 	hammer_buffer_t buffer1 = NULL;
397 	hammer_buffer_t buffer2 = NULL;
398 	hammer_buffer_t buffer3 = NULL;
399 	hammer_off_t tmp_offset;
400 	hammer_off_t next_offset;
401 	hammer_off_t layer1_offset;
402 	hammer_off_t layer2_offset;
403 	hammer_off_t base_off;
404 	hammer_reserve_t resv;
405 	hammer_reserve_t resx;
406 	int loops = 0;
407 	int offset;
408 
409 	/*
410 	 * Setup
411 	 */
412 	KKASSERT(zone >= HAMMER_ZONE_BTREE_INDEX && zone < HAMMER_MAX_ZONES);
413 	root_volume = hammer_get_root_volume(hmp, errorp);
414 	if (*errorp)
415 		return(NULL);
416 	blockmap = &hmp->blockmap[zone];
417 	freemap = &hmp->blockmap[HAMMER_ZONE_FREEMAP_INDEX];
418 	KKASSERT(HAMMER_ZONE_DECODE(blockmap->next_offset) == zone);
419 
420 	/*
421 	 * Deal with alignment and buffer-boundary issues.
422 	 *
423 	 * Be careful, certain primary alignments are used below to allocate
424 	 * new blockmap blocks.
425 	 */
426 	bytes = (bytes + 15) & ~15;
427 	KKASSERT(bytes > 0 && bytes <= HAMMER_XBUFSIZE);
428 
429 	next_offset = blockmap->next_offset;
430 again:
431 	resv = NULL;
432 	/*
433 	 * Check for wrap
434 	 */
435 	if (next_offset == HAMMER_ZONE_ENCODE(zone + 1, 0)) {
436 		if (++loops == 2) {
437 			*errorp = ENOSPC;
438 			goto failed;
439 		}
440 		next_offset = HAMMER_ZONE_ENCODE(zone, 0);
441 	}
442 
443 	/*
444 	 * The allocation request may not cross a buffer boundary.  Special
445 	 * large allocations must not cross a large-block boundary.
446 	 */
447 	tmp_offset = next_offset + bytes - 1;
448 	if (bytes <= HAMMER_BUFSIZE) {
449 		if ((next_offset ^ tmp_offset) & ~HAMMER_BUFMASK64) {
450 			next_offset = tmp_offset & ~HAMMER_BUFMASK64;
451 			goto again;
452 		}
453 	} else {
454 		if ((next_offset ^ tmp_offset) & ~HAMMER_LARGEBLOCK_MASK64) {
455 			next_offset = tmp_offset & ~HAMMER_LARGEBLOCK_MASK64;
456 			goto again;
457 		}
458 	}
459 	offset = (int)next_offset & HAMMER_LARGEBLOCK_MASK;
460 
461 	/*
462 	 * Dive layer 1.
463 	 */
464 	layer1_offset = freemap->phys_offset +
465 			HAMMER_BLOCKMAP_LAYER1_OFFSET(next_offset);
466 	layer1 = hammer_bread(hmp, layer1_offset, errorp, &buffer1);
467 	if (*errorp)
468 		goto failed;
469 
470 	/*
471 	 * Check CRC.
472 	 */
473 	if (layer1->layer1_crc != crc32(layer1, HAMMER_LAYER1_CRCSIZE)) {
474 		hammer_lock_ex(&hmp->blkmap_lock);
475 		if (layer1->layer1_crc != crc32(layer1, HAMMER_LAYER1_CRCSIZE))
476 			panic("CRC FAILED: LAYER1");
477 		hammer_unlock(&hmp->blkmap_lock);
478 	}
479 
480 	/*
481 	 * If we are at a big-block boundary and layer1 indicates no
482 	 * free big-blocks, then we cannot allocate a new bigblock in
483 	 * layer2, skip to the next layer1 entry.
484 	 */
485 	if ((next_offset & HAMMER_LARGEBLOCK_MASK) == 0 &&
486 	    layer1->blocks_free == 0) {
487 		next_offset = (next_offset + HAMMER_BLOCKMAP_LAYER2) &
488 			      ~HAMMER_BLOCKMAP_LAYER2_MASK;
489 		goto again;
490 	}
491 	KKASSERT(layer1->phys_offset != HAMMER_BLOCKMAP_UNAVAIL);
492 
493 	/*
494 	 * Dive layer 2, each entry represents a large-block.
495 	 */
496 	layer2_offset = layer1->phys_offset +
497 			HAMMER_BLOCKMAP_LAYER2_OFFSET(next_offset);
498 	layer2 = hammer_bread(hmp, layer2_offset, errorp, &buffer2);
499 	if (*errorp)
500 		goto failed;
501 
502 	/*
503 	 * Check CRC if not allocating into uninitialized space (which we
504 	 * aren't when reserving space).
505 	 */
506 	if (layer2->entry_crc != crc32(layer2, HAMMER_LAYER2_CRCSIZE)) {
507 		hammer_lock_ex(&hmp->blkmap_lock);
508 		if (layer2->entry_crc != crc32(layer2, HAMMER_LAYER2_CRCSIZE))
509 			panic("CRC FAILED: LAYER2");
510 		hammer_unlock(&hmp->blkmap_lock);
511 	}
512 
513 	/*
514 	 * Skip the layer if the zone is owned by someone other then us.
515 	 */
516 	if (layer2->zone && layer2->zone != zone) {
517 		next_offset += (HAMMER_LARGEBLOCK_SIZE - offset);
518 		goto again;
519 	}
520 	if (offset < layer2->append_off) {
521 		next_offset += layer2->append_off - offset;
522 		goto again;
523 	}
524 
525 	/*
526 	 * We need the lock from this point on.  We have to re-check zone
527 	 * ownership after acquiring the lock and also check for reservations.
528 	 */
529 	hammer_lock_ex(&hmp->blkmap_lock);
530 
531 	if (layer2->zone && layer2->zone != zone) {
532 		hammer_unlock(&hmp->blkmap_lock);
533 		next_offset += (HAMMER_LARGEBLOCK_SIZE - offset);
534 		goto again;
535 	}
536 	if (offset < layer2->append_off) {
537 		hammer_unlock(&hmp->blkmap_lock);
538 		next_offset += layer2->append_off - offset;
539 		goto again;
540 	}
541 
542 	/*
543 	 * The bigblock might be reserved by another zone.  If it is reserved
544 	 * by our zone we may have to move next_offset past the append_off.
545 	 */
546 	base_off = (next_offset &
547 		    (~HAMMER_LARGEBLOCK_MASK64 & ~HAMMER_OFF_ZONE_MASK)) |
548 		    HAMMER_ZONE_RAW_BUFFER;
549 	resv = RB_LOOKUP(hammer_res_rb_tree, &hmp->rb_resv_root, base_off);
550 	if (resv) {
551 		if (resv->zone != zone) {
552 			hammer_unlock(&hmp->blkmap_lock);
553 			next_offset = (next_offset + HAMMER_LARGEBLOCK_SIZE) &
554 				      ~HAMMER_LARGEBLOCK_MASK64;
555 			goto again;
556 		}
557 		if (offset < resv->append_off) {
558 			hammer_unlock(&hmp->blkmap_lock);
559 			next_offset += resv->append_off - offset;
560 			goto again;
561 		}
562 		++resv->refs;
563 		resx = NULL;
564 	} else {
565 		resx = kmalloc(sizeof(*resv), hmp->m_misc,
566 			       M_WAITOK | M_ZERO | M_USE_RESERVE);
567 		resx->refs = 1;
568 		resx->zone = zone;
569 		resx->zone_offset = base_off;
570 		if (layer2->bytes_free == HAMMER_LARGEBLOCK_SIZE)
571 			resx->flags |= HAMMER_RESF_LAYER2FREE;
572 		resv = RB_INSERT(hammer_res_rb_tree, &hmp->rb_resv_root, resx);
573 		KKASSERT(resv == NULL);
574 		resv = resx;
575 		++hammer_count_reservations;
576 	}
577 	resv->append_off = offset + bytes;
578 
579 	/*
580 	 * If we are not reserving a whole buffer but are at the start of
581 	 * a new block, call hammer_bnew() to avoid a disk read.
582 	 *
583 	 * If we are reserving a whole buffer (or more), the caller will
584 	 * probably use a direct read, so do nothing.
585 	 */
586 	if (bytes < HAMMER_BUFSIZE && (next_offset & HAMMER_BUFMASK) == 0) {
587 		hammer_bnew(hmp, next_offset, errorp, &buffer3);
588 	}
589 
590 	/*
591 	 * Adjust our iterator and alloc_offset.  The layer1 and layer2
592 	 * space beyond alloc_offset is uninitialized.  alloc_offset must
593 	 * be big-block aligned.
594 	 */
595 	blockmap->next_offset = next_offset + bytes;
596 	hammer_unlock(&hmp->blkmap_lock);
597 
598 failed:
599 	if (buffer1)
600 		hammer_rel_buffer(buffer1, 0);
601 	if (buffer2)
602 		hammer_rel_buffer(buffer2, 0);
603 	if (buffer3)
604 		hammer_rel_buffer(buffer3, 0);
605 	hammer_rel_volume(root_volume, 0);
606 	*zone_offp = next_offset;
607 
608 	return(resv);
609 }
610 
611 /*
612  * Dereference a reservation structure.  Upon the final release the
613  * underlying big-block is checked and if it is entirely free we delete
614  * any related HAMMER buffers to avoid potential conflicts with future
615  * reuse of the big-block.
616  */
617 void
618 hammer_blockmap_reserve_complete(hammer_mount_t hmp, hammer_reserve_t resv)
619 {
620 	hammer_off_t base_offset;
621 	int error;
622 
623 	KKASSERT(resv->refs > 0);
624 	KKASSERT((resv->zone_offset & HAMMER_OFF_ZONE_MASK) ==
625 		 HAMMER_ZONE_RAW_BUFFER);
626 
627 	/*
628 	 * Setting append_off to the max prevents any new allocations
629 	 * from occuring while we are trying to dispose of the reservation,
630 	 * allowing us to safely delete any related HAMMER buffers.
631 	 *
632 	 * If we are unable to clean out all related HAMMER buffers we
633 	 * requeue the delay.
634 	 */
635 	if (resv->refs == 1 && (resv->flags & HAMMER_RESF_LAYER2FREE)) {
636 		resv->append_off = HAMMER_LARGEBLOCK_SIZE;
637 		base_offset = resv->zone_offset & ~HAMMER_OFF_ZONE_MASK;
638 		base_offset = HAMMER_ZONE_ENCODE(resv->zone, base_offset);
639 		error = hammer_del_buffers(hmp, base_offset,
640 					   resv->zone_offset,
641 					   HAMMER_LARGEBLOCK_SIZE,
642 					   0);
643 		if (error)
644 			hammer_reserve_setdelay(hmp, resv);
645 	}
646 	if (--resv->refs == 0) {
647 		KKASSERT((resv->flags & HAMMER_RESF_ONDELAY) == 0);
648 		RB_REMOVE(hammer_res_rb_tree, &hmp->rb_resv_root, resv);
649 		kfree(resv, hmp->m_misc);
650 		--hammer_count_reservations;
651 	}
652 }
653 
654 /*
655  * Prevent a potentially free big-block from being reused until after
656  * the related flushes have completely cycled, otherwise crash recovery
657  * could resurrect a data block that was already reused and overwritten.
658  *
659  * The caller might reset the underlying layer2 entry's append_off to 0, so
660  * our covering append_off must be set to max to prevent any reallocation
661  * until after the flush delays complete, not to mention proper invalidation
662  * of any underlying cached blocks.
663  */
664 static void
665 hammer_reserve_setdelay_offset(hammer_mount_t hmp, hammer_off_t base_offset,
666 			int zone, struct hammer_blockmap_layer2 *layer2)
667 {
668 	hammer_reserve_t resv;
669 
670 	/*
671 	 * Allocate the reservation if necessary.
672 	 *
673 	 * NOTE: need lock in future around resv lookup/allocation and
674 	 * the setdelay call, currently refs is not bumped until the call.
675 	 */
676 again:
677 	resv = RB_LOOKUP(hammer_res_rb_tree, &hmp->rb_resv_root, base_offset);
678 	if (resv == NULL) {
679 		resv = kmalloc(sizeof(*resv), hmp->m_misc,
680 			       M_WAITOK | M_ZERO | M_USE_RESERVE);
681 		resv->zone = zone;
682 		resv->zone_offset = base_offset;
683 		resv->refs = 0;
684 		resv->append_off = HAMMER_LARGEBLOCK_SIZE;
685 
686 		if (layer2->bytes_free == HAMMER_LARGEBLOCK_SIZE)
687 			resv->flags |= HAMMER_RESF_LAYER2FREE;
688 		if (RB_INSERT(hammer_res_rb_tree, &hmp->rb_resv_root, resv)) {
689 			kfree(resv, hmp->m_misc);
690 			goto again;
691 		}
692 		++hammer_count_reservations;
693 	} else {
694 		if (layer2->bytes_free == HAMMER_LARGEBLOCK_SIZE)
695 			resv->flags |= HAMMER_RESF_LAYER2FREE;
696 	}
697 	hammer_reserve_setdelay(hmp, resv);
698 }
699 
700 /*
701  * Enter the reservation on the on-delay list, or move it if it
702  * is already on the list.
703  */
704 static void
705 hammer_reserve_setdelay(hammer_mount_t hmp, hammer_reserve_t resv)
706 {
707 	if (resv->flags & HAMMER_RESF_ONDELAY) {
708 		TAILQ_REMOVE(&hmp->delay_list, resv, delay_entry);
709 		resv->flush_group = hmp->flusher.next + 1;
710 		TAILQ_INSERT_TAIL(&hmp->delay_list, resv, delay_entry);
711 	} else {
712 		++resv->refs;
713 		++hmp->rsv_fromdelay;
714 		resv->flags |= HAMMER_RESF_ONDELAY;
715 		resv->flush_group = hmp->flusher.next + 1;
716 		TAILQ_INSERT_TAIL(&hmp->delay_list, resv, delay_entry);
717 	}
718 }
719 
720 void
721 hammer_reserve_clrdelay(hammer_mount_t hmp, hammer_reserve_t resv)
722 {
723 	KKASSERT(resv->flags & HAMMER_RESF_ONDELAY);
724 	resv->flags &= ~HAMMER_RESF_ONDELAY;
725 	TAILQ_REMOVE(&hmp->delay_list, resv, delay_entry);
726 	--hmp->rsv_fromdelay;
727 	hammer_blockmap_reserve_complete(hmp, resv);
728 }
729 
730 /*
731  * Backend function - free (offset, bytes) in a zone.
732  *
733  * XXX error return
734  */
735 void
736 hammer_blockmap_free(hammer_transaction_t trans,
737 		     hammer_off_t zone_offset, int bytes)
738 {
739 	hammer_mount_t hmp;
740 	hammer_volume_t root_volume;
741 	hammer_blockmap_t blockmap;
742 	hammer_blockmap_t freemap;
743 	struct hammer_blockmap_layer1 *layer1;
744 	struct hammer_blockmap_layer2 *layer2;
745 	hammer_buffer_t buffer1 = NULL;
746 	hammer_buffer_t buffer2 = NULL;
747 	hammer_off_t layer1_offset;
748 	hammer_off_t layer2_offset;
749 	hammer_off_t base_off;
750 	int error;
751 	int zone;
752 
753 	if (bytes == 0)
754 		return;
755 	hmp = trans->hmp;
756 
757 	/*
758 	 * Alignment
759 	 */
760 	bytes = (bytes + 15) & ~15;
761 	KKASSERT(bytes <= HAMMER_XBUFSIZE);
762 	KKASSERT(((zone_offset ^ (zone_offset + (bytes - 1))) &
763 		  ~HAMMER_LARGEBLOCK_MASK64) == 0);
764 
765 	/*
766 	 * Basic zone validation & locking
767 	 */
768 	zone = HAMMER_ZONE_DECODE(zone_offset);
769 	KKASSERT(zone >= HAMMER_ZONE_BTREE_INDEX && zone < HAMMER_MAX_ZONES);
770 	root_volume = trans->rootvol;
771 	error = 0;
772 
773 	blockmap = &hmp->blockmap[zone];
774 	freemap = &hmp->blockmap[HAMMER_ZONE_FREEMAP_INDEX];
775 
776 	/*
777 	 * Dive layer 1.
778 	 */
779 	layer1_offset = freemap->phys_offset +
780 			HAMMER_BLOCKMAP_LAYER1_OFFSET(zone_offset);
781 	layer1 = hammer_bread(hmp, layer1_offset, &error, &buffer1);
782 	if (error)
783 		goto failed;
784 	KKASSERT(layer1->phys_offset &&
785 		 layer1->phys_offset != HAMMER_BLOCKMAP_UNAVAIL);
786 	if (layer1->layer1_crc != crc32(layer1, HAMMER_LAYER1_CRCSIZE)) {
787 		hammer_lock_ex(&hmp->blkmap_lock);
788 		if (layer1->layer1_crc != crc32(layer1, HAMMER_LAYER1_CRCSIZE))
789 			panic("CRC FAILED: LAYER1");
790 		hammer_unlock(&hmp->blkmap_lock);
791 	}
792 
793 	/*
794 	 * Dive layer 2, each entry represents a large-block.
795 	 */
796 	layer2_offset = layer1->phys_offset +
797 			HAMMER_BLOCKMAP_LAYER2_OFFSET(zone_offset);
798 	layer2 = hammer_bread(hmp, layer2_offset, &error, &buffer2);
799 	if (error)
800 		goto failed;
801 	if (layer2->entry_crc != crc32(layer2, HAMMER_LAYER2_CRCSIZE)) {
802 		hammer_lock_ex(&hmp->blkmap_lock);
803 		if (layer2->entry_crc != crc32(layer2, HAMMER_LAYER2_CRCSIZE))
804 			panic("CRC FAILED: LAYER2");
805 		hammer_unlock(&hmp->blkmap_lock);
806 	}
807 
808 	hammer_lock_ex(&hmp->blkmap_lock);
809 
810 	hammer_modify_buffer(trans, buffer2, layer2, sizeof(*layer2));
811 
812 	/*
813 	 * Free space previously allocated via blockmap_alloc().
814 	 */
815 	KKASSERT(layer2->zone == zone);
816 	layer2->bytes_free += bytes;
817 	KKASSERT(layer2->bytes_free <= HAMMER_LARGEBLOCK_SIZE);
818 
819 	/*
820 	 * If a big-block becomes entirely free we must create a covering
821 	 * reservation to prevent premature reuse.  Note, however, that
822 	 * the big-block and/or reservation may still have an append_off
823 	 * that allows further (non-reused) allocations.
824 	 *
825 	 * Once the reservation has been made we re-check layer2 and if
826 	 * the big-block is still entirely free we reset the layer2 entry.
827 	 * The reservation will prevent premature reuse.
828 	 *
829 	 * NOTE: hammer_buffer's are only invalidated when the reservation
830 	 * is completed, if the layer2 entry is still completely free at
831 	 * that time.  Any allocations from the reservation that may have
832 	 * occured in the mean time, or active references on the reservation
833 	 * from new pending allocations, will prevent the invalidation from
834 	 * occuring.
835 	 */
836 	if (layer2->bytes_free == HAMMER_LARGEBLOCK_SIZE) {
837 		base_off = (zone_offset & (~HAMMER_LARGEBLOCK_MASK64 & ~HAMMER_OFF_ZONE_MASK)) | HAMMER_ZONE_RAW_BUFFER;
838 
839 		hammer_reserve_setdelay_offset(hmp, base_off, zone, layer2);
840 		if (layer2->bytes_free == HAMMER_LARGEBLOCK_SIZE) {
841 			layer2->zone = 0;
842 			layer2->append_off = 0;
843 			hammer_modify_buffer(trans, buffer1,
844 					     layer1, sizeof(*layer1));
845 			++layer1->blocks_free;
846 			layer1->layer1_crc = crc32(layer1,
847 						   HAMMER_LAYER1_CRCSIZE);
848 			hammer_modify_buffer_done(buffer1);
849 			hammer_modify_volume_field(trans,
850 					trans->rootvol,
851 					vol0_stat_freebigblocks);
852 			++root_volume->ondisk->vol0_stat_freebigblocks;
853 			hmp->copy_stat_freebigblocks =
854 			   root_volume->ondisk->vol0_stat_freebigblocks;
855 			hammer_modify_volume_done(trans->rootvol);
856 		}
857 	}
858 	layer2->entry_crc = crc32(layer2, HAMMER_LAYER2_CRCSIZE);
859 	hammer_modify_buffer_done(buffer2);
860 	hammer_unlock(&hmp->blkmap_lock);
861 
862 failed:
863 	if (buffer1)
864 		hammer_rel_buffer(buffer1, 0);
865 	if (buffer2)
866 		hammer_rel_buffer(buffer2, 0);
867 }
868 
869 /*
870  * Backend function - finalize (offset, bytes) in a zone.
871  *
872  * Allocate space that was previously reserved by the frontend.
873  */
874 int
875 hammer_blockmap_finalize(hammer_transaction_t trans,
876 			 hammer_reserve_t resv,
877 			 hammer_off_t zone_offset, int bytes)
878 {
879 	hammer_mount_t hmp;
880 	hammer_volume_t root_volume;
881 	hammer_blockmap_t blockmap;
882 	hammer_blockmap_t freemap;
883 	struct hammer_blockmap_layer1 *layer1;
884 	struct hammer_blockmap_layer2 *layer2;
885 	hammer_buffer_t buffer1 = NULL;
886 	hammer_buffer_t buffer2 = NULL;
887 	hammer_off_t layer1_offset;
888 	hammer_off_t layer2_offset;
889 	int error;
890 	int zone;
891 	int offset;
892 
893 	if (bytes == 0)
894 		return(0);
895 	hmp = trans->hmp;
896 
897 	/*
898 	 * Alignment
899 	 */
900 	bytes = (bytes + 15) & ~15;
901 	KKASSERT(bytes <= HAMMER_XBUFSIZE);
902 
903 	/*
904 	 * Basic zone validation & locking
905 	 */
906 	zone = HAMMER_ZONE_DECODE(zone_offset);
907 	KKASSERT(zone >= HAMMER_ZONE_BTREE_INDEX && zone < HAMMER_MAX_ZONES);
908 	root_volume = trans->rootvol;
909 	error = 0;
910 
911 	blockmap = &hmp->blockmap[zone];
912 	freemap = &hmp->blockmap[HAMMER_ZONE_FREEMAP_INDEX];
913 
914 	/*
915 	 * Dive layer 1.
916 	 */
917 	layer1_offset = freemap->phys_offset +
918 			HAMMER_BLOCKMAP_LAYER1_OFFSET(zone_offset);
919 	layer1 = hammer_bread(hmp, layer1_offset, &error, &buffer1);
920 	if (error)
921 		goto failed;
922 	KKASSERT(layer1->phys_offset &&
923 		 layer1->phys_offset != HAMMER_BLOCKMAP_UNAVAIL);
924 	if (layer1->layer1_crc != crc32(layer1, HAMMER_LAYER1_CRCSIZE)) {
925 		hammer_lock_ex(&hmp->blkmap_lock);
926 		if (layer1->layer1_crc != crc32(layer1, HAMMER_LAYER1_CRCSIZE))
927 			panic("CRC FAILED: LAYER1");
928 		hammer_unlock(&hmp->blkmap_lock);
929 	}
930 
931 	/*
932 	 * Dive layer 2, each entry represents a large-block.
933 	 */
934 	layer2_offset = layer1->phys_offset +
935 			HAMMER_BLOCKMAP_LAYER2_OFFSET(zone_offset);
936 	layer2 = hammer_bread(hmp, layer2_offset, &error, &buffer2);
937 	if (error)
938 		goto failed;
939 	if (layer2->entry_crc != crc32(layer2, HAMMER_LAYER2_CRCSIZE)) {
940 		hammer_lock_ex(&hmp->blkmap_lock);
941 		if (layer2->entry_crc != crc32(layer2, HAMMER_LAYER2_CRCSIZE))
942 			panic("CRC FAILED: LAYER2");
943 		hammer_unlock(&hmp->blkmap_lock);
944 	}
945 
946 	hammer_lock_ex(&hmp->blkmap_lock);
947 
948 	hammer_modify_buffer(trans, buffer2, layer2, sizeof(*layer2));
949 
950 	/*
951 	 * Finalize some or all of the space covered by a current
952 	 * reservation.  An allocation in the same layer may have
953 	 * already assigned ownership.
954 	 */
955 	if (layer2->zone == 0) {
956 		hammer_modify_buffer(trans, buffer1,
957 				     layer1, sizeof(*layer1));
958 		--layer1->blocks_free;
959 		layer1->layer1_crc = crc32(layer1,
960 					   HAMMER_LAYER1_CRCSIZE);
961 		hammer_modify_buffer_done(buffer1);
962 		layer2->zone = zone;
963 		KKASSERT(layer2->bytes_free == HAMMER_LARGEBLOCK_SIZE);
964 		KKASSERT(layer2->append_off == 0);
965 		hammer_modify_volume_field(trans,
966 				trans->rootvol,
967 				vol0_stat_freebigblocks);
968 		--root_volume->ondisk->vol0_stat_freebigblocks;
969 		hmp->copy_stat_freebigblocks =
970 		   root_volume->ondisk->vol0_stat_freebigblocks;
971 		hammer_modify_volume_done(trans->rootvol);
972 	}
973 	if (layer2->zone != zone)
974 		kprintf("layer2 zone mismatch %d %d\n", layer2->zone, zone);
975 	KKASSERT(layer2->zone == zone);
976 	KKASSERT(bytes != 0);
977 	layer2->bytes_free -= bytes;
978 	if (resv)
979 		resv->flags &= ~HAMMER_RESF_LAYER2FREE;
980 
981 	/*
982 	 * Finalizations can occur out of order, or combined with allocations.
983 	 * append_off must be set to the highest allocated offset.
984 	 */
985 	offset = ((int)zone_offset & HAMMER_LARGEBLOCK_MASK) + bytes;
986 	if (layer2->append_off < offset)
987 		layer2->append_off = offset;
988 
989 	layer2->entry_crc = crc32(layer2, HAMMER_LAYER2_CRCSIZE);
990 	hammer_modify_buffer_done(buffer2);
991 	hammer_unlock(&hmp->blkmap_lock);
992 
993 failed:
994 	if (buffer1)
995 		hammer_rel_buffer(buffer1, 0);
996 	if (buffer2)
997 		hammer_rel_buffer(buffer2, 0);
998 	return(error);
999 }
1000 
1001 /*
1002  * Return the number of free bytes in the big-block containing the
1003  * specified blockmap offset.
1004  */
1005 int
1006 hammer_blockmap_getfree(hammer_mount_t hmp, hammer_off_t zone_offset,
1007 			int *curp, int *errorp)
1008 {
1009 	hammer_volume_t root_volume;
1010 	hammer_blockmap_t blockmap;
1011 	hammer_blockmap_t freemap;
1012 	struct hammer_blockmap_layer1 *layer1;
1013 	struct hammer_blockmap_layer2 *layer2;
1014 	hammer_buffer_t buffer = NULL;
1015 	hammer_off_t layer1_offset;
1016 	hammer_off_t layer2_offset;
1017 	int bytes;
1018 	int zone;
1019 
1020 	zone = HAMMER_ZONE_DECODE(zone_offset);
1021 	KKASSERT(zone >= HAMMER_ZONE_BTREE_INDEX && zone < HAMMER_MAX_ZONES);
1022 	root_volume = hammer_get_root_volume(hmp, errorp);
1023 	if (*errorp) {
1024 		*curp = 0;
1025 		return(0);
1026 	}
1027 	blockmap = &hmp->blockmap[zone];
1028 	freemap = &hmp->blockmap[HAMMER_ZONE_FREEMAP_INDEX];
1029 
1030 	/*
1031 	 * Dive layer 1.
1032 	 */
1033 	layer1_offset = freemap->phys_offset +
1034 			HAMMER_BLOCKMAP_LAYER1_OFFSET(zone_offset);
1035 	layer1 = hammer_bread(hmp, layer1_offset, errorp, &buffer);
1036 	if (*errorp) {
1037 		bytes = 0;
1038 		goto failed;
1039 	}
1040 	KKASSERT(layer1->phys_offset);
1041 	if (layer1->layer1_crc != crc32(layer1, HAMMER_LAYER1_CRCSIZE)) {
1042 		hammer_lock_ex(&hmp->blkmap_lock);
1043 		if (layer1->layer1_crc != crc32(layer1, HAMMER_LAYER1_CRCSIZE))
1044 			panic("CRC FAILED: LAYER1");
1045 		hammer_unlock(&hmp->blkmap_lock);
1046 	}
1047 
1048 	/*
1049 	 * Dive layer 2, each entry represents a large-block.
1050 	 *
1051 	 * (reuse buffer, layer1 pointer becomes invalid)
1052 	 */
1053 	layer2_offset = layer1->phys_offset +
1054 			HAMMER_BLOCKMAP_LAYER2_OFFSET(zone_offset);
1055 	layer2 = hammer_bread(hmp, layer2_offset, errorp, &buffer);
1056 	if (*errorp) {
1057 		bytes = 0;
1058 		goto failed;
1059 	}
1060 	if (layer2->entry_crc != crc32(layer2, HAMMER_LAYER2_CRCSIZE)) {
1061 		hammer_lock_ex(&hmp->blkmap_lock);
1062 		if (layer2->entry_crc != crc32(layer2, HAMMER_LAYER2_CRCSIZE))
1063 			panic("CRC FAILED: LAYER2");
1064 		hammer_unlock(&hmp->blkmap_lock);
1065 	}
1066 	KKASSERT(layer2->zone == zone);
1067 
1068 	bytes = layer2->bytes_free;
1069 
1070 	if ((blockmap->next_offset ^ zone_offset) & ~HAMMER_LARGEBLOCK_MASK64)
1071 		*curp = 0;
1072 	else
1073 		*curp = 1;
1074 failed:
1075 	if (buffer)
1076 		hammer_rel_buffer(buffer, 0);
1077 	hammer_rel_volume(root_volume, 0);
1078 	if (hammer_debug_general & 0x0800) {
1079 		kprintf("hammer_blockmap_getfree: %016llx -> %d\n",
1080 			(long long)zone_offset, bytes);
1081 	}
1082 	return(bytes);
1083 }
1084 
1085 
1086 /*
1087  * Lookup a blockmap offset.
1088  */
1089 hammer_off_t
1090 hammer_blockmap_lookup(hammer_mount_t hmp, hammer_off_t zone_offset,
1091 		       int *errorp)
1092 {
1093 	hammer_volume_t root_volume;
1094 	hammer_blockmap_t freemap;
1095 	struct hammer_blockmap_layer1 *layer1;
1096 	struct hammer_blockmap_layer2 *layer2;
1097 	hammer_buffer_t buffer = NULL;
1098 	hammer_off_t layer1_offset;
1099 	hammer_off_t layer2_offset;
1100 	hammer_off_t result_offset;
1101 	hammer_off_t base_off;
1102 	hammer_reserve_t resv;
1103 	int zone;
1104 
1105 	/*
1106 	 * Calculate the zone-2 offset.
1107 	 */
1108 	zone = HAMMER_ZONE_DECODE(zone_offset);
1109 	KKASSERT(zone >= HAMMER_ZONE_BTREE_INDEX && zone < HAMMER_MAX_ZONES);
1110 
1111 	result_offset = (zone_offset & ~HAMMER_OFF_ZONE_MASK) |
1112 			HAMMER_ZONE_RAW_BUFFER;
1113 
1114 	/*
1115 	 * We can actually stop here, normal blockmaps are now direct-mapped
1116 	 * onto the freemap and so represent zone-2 addresses.
1117 	 */
1118 	if (hammer_verify_zone == 0) {
1119 		*errorp = 0;
1120 		return(result_offset);
1121 	}
1122 
1123 	/*
1124 	 * Validate the allocation zone
1125 	 */
1126 	root_volume = hammer_get_root_volume(hmp, errorp);
1127 	if (*errorp)
1128 		return(0);
1129 	freemap = &hmp->blockmap[HAMMER_ZONE_FREEMAP_INDEX];
1130 	KKASSERT(freemap->phys_offset != 0);
1131 
1132 	/*
1133 	 * Dive layer 1.
1134 	 */
1135 	layer1_offset = freemap->phys_offset +
1136 			HAMMER_BLOCKMAP_LAYER1_OFFSET(zone_offset);
1137 	layer1 = hammer_bread(hmp, layer1_offset, errorp, &buffer);
1138 	if (*errorp)
1139 		goto failed;
1140 	KKASSERT(layer1->phys_offset != HAMMER_BLOCKMAP_UNAVAIL);
1141 	if (layer1->layer1_crc != crc32(layer1, HAMMER_LAYER1_CRCSIZE)) {
1142 		hammer_lock_ex(&hmp->blkmap_lock);
1143 		if (layer1->layer1_crc != crc32(layer1, HAMMER_LAYER1_CRCSIZE))
1144 			panic("CRC FAILED: LAYER1");
1145 		hammer_unlock(&hmp->blkmap_lock);
1146 	}
1147 
1148 	/*
1149 	 * Dive layer 2, each entry represents a large-block.
1150 	 */
1151 	layer2_offset = layer1->phys_offset +
1152 			HAMMER_BLOCKMAP_LAYER2_OFFSET(zone_offset);
1153 	layer2 = hammer_bread(hmp, layer2_offset, errorp, &buffer);
1154 
1155 	if (*errorp)
1156 		goto failed;
1157 	if (layer2->zone == 0) {
1158 		base_off = (zone_offset & (~HAMMER_LARGEBLOCK_MASK64 & ~HAMMER_OFF_ZONE_MASK)) | HAMMER_ZONE_RAW_BUFFER;
1159 		resv = RB_LOOKUP(hammer_res_rb_tree, &hmp->rb_resv_root,
1160 				 base_off);
1161 		KKASSERT(resv && resv->zone == zone);
1162 
1163 	} else if (layer2->zone != zone) {
1164 		panic("hammer_blockmap_lookup: bad zone %d/%d\n",
1165 			layer2->zone, zone);
1166 	}
1167 	if (layer2->entry_crc != crc32(layer2, HAMMER_LAYER2_CRCSIZE)) {
1168 		hammer_lock_ex(&hmp->blkmap_lock);
1169 		if (layer2->entry_crc != crc32(layer2, HAMMER_LAYER2_CRCSIZE))
1170 			panic("CRC FAILED: LAYER2");
1171 		hammer_unlock(&hmp->blkmap_lock);
1172 	}
1173 
1174 failed:
1175 	if (buffer)
1176 		hammer_rel_buffer(buffer, 0);
1177 	hammer_rel_volume(root_volume, 0);
1178 	if (hammer_debug_general & 0x0800) {
1179 		kprintf("hammer_blockmap_lookup: %016llx -> %016llx\n",
1180 			(long long)zone_offset, (long long)result_offset);
1181 	}
1182 	return(result_offset);
1183 }
1184 
1185 
1186 /*
1187  * Check space availability
1188  */
1189 int
1190 _hammer_checkspace(hammer_mount_t hmp, int slop, int64_t *resp)
1191 {
1192 	const int in_size = sizeof(struct hammer_inode_data) +
1193 			    sizeof(union hammer_btree_elm);
1194 	const int rec_size = (sizeof(union hammer_btree_elm) * 2);
1195 	int64_t usedbytes;
1196 
1197 	usedbytes = hmp->rsv_inodes * in_size +
1198 		    hmp->rsv_recs * rec_size +
1199 		    hmp->rsv_databytes +
1200 		    ((int64_t)hmp->rsv_fromdelay << HAMMER_LARGEBLOCK_BITS) +
1201 		    ((int64_t)hidirtybufspace << 2) +
1202 		    (slop << HAMMER_LARGEBLOCK_BITS);
1203 
1204 	hammer_count_extra_space_used = usedbytes;	/* debugging */
1205 	if (resp)
1206 		*resp = usedbytes;
1207 
1208 	if (hmp->copy_stat_freebigblocks >=
1209 	    (usedbytes >> HAMMER_LARGEBLOCK_BITS)) {
1210 		return(0);
1211 	}
1212 	return (ENOSPC);
1213 }
1214 
1215